Folded fabric gasket and method of manufacture



Jan. 18, 1949. E. J. POLTORAK 2,459,720

FOLDED FABRIC GASKET AND METHOD OF MANUFACTURE Filed March 19, 1945 IN VEN TOR.

- 514/; J #04 7'0A4/f I A/WJEKZM' A 770/?NE X Patented Jan. 18, 1949FOLDED FABRIC GASKET AND METHOD OF MANUFACTURE Emil J. Poitorak, SomJohns-Manville Corp crville, N. J., assignor to oration, New York, N.Y.,

a corporaiion of New York Application March 19, 1945, Serial No. 583,543

This invention relates to a jacketed gasket, and particularly to amethod of providing a folded fabric gasket with a thin, flexible casingor jacket of solvent and heat resistant material,

A primary object of the invention is to provide a folded fabric gasketwith a thin, flexible jacket of insoluble heat-resistant material whichcannot be applied by conventional coating methods.

The invention is particularly concerned with the problem of providinggaskets having the properties of heat resistance and softness orresilience which are inherent to the asbestos fabric type ofconstruction, and which shall also be adapted to withstand thedisintegrating action of strong chemicals. Certain synthetic plastics orelastomers are available in thin, flexible tape form which resist theaction of all known solvents and chemicals, and which have softening ormelting points above 500 F. Since such plastics are solvent resistantand substantially infusible, they cannot be applied practically byconventional coating, spraying or dipping methods.

A further object is therefore to provide a method whereby a thin,flexible ribbon or tape of chemical and solvent-proof plastic of highmelting point may be applied as a protective jacket for the exposedsurfaces of a felted fabric gasket.

A particular object is to provide a felted fabric gasket with a thin,flexible tape jacket which will protect the gasket against strongchemicals such as hot concentrated nitric acid, and which will notimpair the resilient qualities of-the gasket while providing theexterior exposed surfaces thereof with a non-adherent, non-tackycovering.

With the aforementioned objects and features in view, the inventionconsists in the improved jacketed gasket and method of manufacture whichare hereinafter described and more particularly defined by theaccompanying claims.

In the following description of a preferred form of the invention,reference will be made to the attached drawings, in which:

Fig. 1 is a transverse cross-section through a flange coupling which hasbeen sealed by a jacketed folded fabric asket embodying the invention;and

Fig. 2 is an enlarged cross section, with a part in elevation, of asmall portion of a folded fabric ring gasket having a heat and solventresistant, flexible tape jacket.

As shown in the drawings, the jacketed fabric gasket of the presentinvention may comprise a strip of fibrous fabric having its ends joinedto form a collar and folded along its center line it and rolled to forma ring M. The edges I6 of 2 Claims. (Cl. 28833).

the strip may be folded inwardly as at 18. The folded fabric ring isprotected against contact with corrosive or hot liquids or vapors by athin jacket 20 comprising a flexible tape of heat and solvent resistantmaterial having its ends joined. The jacket tape is also folded alongits center line 22, and its edges 24 are folded inwardly at 25 in lappedjoint relation between the lapped inside surfaces of ring M.

One type of flexible material suitable for forming jacket 20 consists ofa highly polymerized synthetic resin, tetrafluor ethylene polymer, whichresists all known solvents and chemicals and which is available in theform of a flexible tape of 3 inch width and .003 inch thickness.

Since this material is insoluble, it cannot be used in the form of asolution or cement for coating the fabric gasket as by painting,spraying or dipping. Moreover, since this plastic material is highlyheat resistant, and has a softening temperature above 500 F., it cannotbe applied in liquid form or by conventional calendering or frictioncoating equipment. Certain kinds of flexible metal foil may also be usedfor forming the jacket.

For forming a ring shaped gasket such as illustrated in the drawings, astrip ill of woven asbestos fabric may be impregnated or otherwisetreated with a rubber or with a synethetic resinous material. Thethus-treated fabric strip may be cut on the necessary by experience toproduce a folded fabric ring gasket of the type illustrated. The biascut ends of the fabric strip are joined and rolled to form a cylindricalcollar and the first outward folds iii are made to bring the edges I6into spaced relation with a spacing between them of about twice thefabric thickness. A strip of plastic tape 20 of suitable length is nowcoated on one side with an adhesive cement, and after a proper dryingperiod the cement coated side of gasket. The edges 24 of the tape thetape is applied longitudinally to the inner surface of the fabriccollar, with the lateral edges -24 of the plastic tape overhanging byapproximately equal amounts on each side of the center line i2 of thefolded fabric collar. The ends of the plastic tape are joined in a lapjoint, and a coating of adhesive is applied to an area of the joinedends which will fold against the gasket. After a suitable drying period,the ends of the tape are cemented to the body of the are folded againstthe folded lapped surfaces of the fabric collar and a coating ofadhesive cement may be applied to the outer surfaces 28 of the foldedbias to the length and width found the body of portions of the tape toadhere such surfaces in a lapped joint. The thus folded fabriccollar,'and its adhering folded tape jacket are again folded along thecentral line of the collar in such a manner that the folded-lateraledges of the fabric and the laterial edges ofthe plastic tape are lappedand cemented together and concealed in the central body portion of thegasket. The jacketed ring gasket thus formed may be finished in aconventional manner, as by rolling and blocking. In this manner a foldedfour ply gasket of 5 /2 inch inside diameter and 7 inch outside diametermay be jacketed by a plastic tape which jacket may be made up intogaskets of rectangular I as well as curved. form.

When the principal central rolled fold I: of the gasket and its encasingjacket lie on the inside diameter of the ring as shown in Fig. l, thegasket is fully protected from attack by hot gases or liquid, such forexample as hot concentrated nitric acid. The illustrated assembly of thejacketed gasket is such as to seal off any portions thereof which mightbe vulnerable against contact with gases or liquids flowing through thepipe joint.

Since many variations may be made from the illustrative details given,without departing from the scope of the invention, it is intended thatthe invention should be limited only by the terms of the claims.

What I claim is:

1. A gasket comprising a fibrous fabric strip having its ends joined andhaving each lateral edge folded outwardly at one side thereof to form aring. a thin flexible heat and solvent resistant tape of polytetrafluorethylene having one surface thereof coated with adhesive and affixedlongitudinally to the inner surface of the ring, the lateral edges ofsaid tape being folded in lapped relation with, the lapped outersurfaces of the fabric ring, the thus-jacketed ring being again foldedalong its center line and rolled to form a multiple ply ring gasket.

2. That method of forming a heat and solvent resistant ring gasket whichcomprises, joining bias cut ends of a fibrous fabric strip to form acylindrical collar and folding both edges of the collar outwardly at oneside thereof to form a ring, amxing one surface of a thin flexible heatand solvent'resistant tape to the inner surface of the ring and foldingthe edges of the tape-in lapped relation with the lapped outer surfacesof the fabric ring, and again folding the thus-jacketed -fabric ringalong its center line and rolling it to form a multi-ply ring gasket.

EMIL J. POLTORAK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

